1. Technical Field
The disclosure relates generally to methods of interfacing insulation parts, and more particularly, to methods of interfacing insulation parts in a high voltage environment.
2. Background Art
Ion implantation is a standard technique for introducing conductivity altering impurities into, or doping, semiconductor wafers. A typical ion implantation process uses an energetic ion beam to introduce impurities (ions) into semiconductor wafers. During ion implantation, a source feed material is energized to generate an ion beam, and the generated ion beam needs to be accelerated by an acceleration column. An acceleration column may be required to accelerate an ion beam at, for example, 670 kV.
A structure at a voltage (hereinafter “voltage structure”), also referred to as a “terminal structure”, in an ion implantation system requires insulation to allow the structure to reach the required high voltage, e.g., 670 kV. Choosing insulation materials that can be manufactured in the sizes required for the voltage structure is challenging. As such, fabrication of smaller pieces that can be interfaced to form the insulation for the voltage structure is a reasonable alternative. However, conventional technologies do not provide a solution for interfacing insulation parts in a high voltage environment, e.g., the high voltage of the structure.
One problem faced by conventional interfacing technologies is that to avoid puncture and/or flash over failures (which cause, e.g., an electrical shorting) in the interface between two interfacing insulation parts, the creepage distance along the surface of the interface between two electric potentials of the high voltage environment needs to be long enough. However, it is not preferable to make the insulation parts very thick to achieve the long creepage distance. For example, many plastics have a flashover breakdown in air of 12 kV/inch, which requires a creepage distance of more than 58 inches to avoid a flashover failure in a high voltage environment of, e.g., 670 kV. A breakdown failure caused by puncturing through a material may occur depending upon the dielectric strength of the material. Since many plastics can have dielectric strength of more than 600 kV per inch, it is possible to insulate a voltage structure at 670 kV with approximately 2 inches of plastic (sufficient for design overhead). For a completely sealed cube, this is sufficient. However, where insulation parts are simply interfaced to form the insulation for the voltage structure, problems of surface flashover need to be addressed, especially for designs with short creepage distances between the voltage structure, and the ground. The design rule for surface flashover is typically 10 kV per inch. For a voltage structure at 670 kV, this design rule equates to 67 inches of creepage distance, which is sufficiently large as to present a limitation in design possibilities.